Selecting device for telephone systems



June 19; 1928.

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UNITE-D STATES ALEXANDER BRUNO PREUSS. OF BERLIN, GERMANY, ASSIGNOR T SIEMENS & HALSKE v'Parerrl OFFICE..

AKTIENGESELLSCHAFT, OF WERNERWERK. SIEMEN'SSTADT, NEAR BERLIN, GER- MANY.

SELECTING DEVICE FOR TELEPHONE SYSTEMS.

Application filed'lfarch'l, 1927, Serial N'o. 176,601, and in Germany July 12, 1926.

The invention relates to a selecting device for telephone systems, having stationary i terminals located in groups in a fiat panel lll like terminal bank, these terminals having associated with them groups of movable contacts. In selecting devices of this kind, it is necessary to have two or more movements of the positioning device for the purpose of positioning the movable contacts onto the' stationary terminals of the bank in order to set up a connection. The object of the invention is to simplify such selecting devices, this being mainly achieved according to the invention by a double straight line motion ot the positioning device in the same direction. ,o

According to the invention, the positioning device comprises two movably mounted switch rods. One of these can be moved independently and the other can be moved with then/first mentioned rod. The group selection is effected fby moving the first mentioned rod alone and the terminal Vselection is ei'eclted by means of moving both rods.

`Other features ofthe invention relate to the special construction of the selecting devices, whereby the movement of the two switch rods can be effected by a single motor magnet with the assistance of a coupling devlce. Y' K The invention 1s also concerned with thc A arrangement of the coupling-device and the provision of means forV connecting private branch exchange lines to selecting devices ofthis type.

For the purpose of describing the invention. several embodiments willebe/ referred to by way of example.

Fig. 1 is a diagrammatic sketch View of the selecting device.

Fig. 2 likewise shows a side View of the upper partof the selecting device with the special construction of the movable contacts.

Fig. 3 is a front view of the Fig. v2 with only one, ofthe movable contact sets.

Fig. 4 shows a dierent construction of the selecting device, for which only one motor magnet is used.

Figs. 5 9- show sidev views of dierentv constructions of details for a selecting device having only one motor magnet.

Fig. 10 shows a side View of a selecting of a side device according to the invention, in which the movable contacts are moved in the rcvcrse direction over the bank contacts.

Figs. 11-14 show views, partiall in perspective, of the arrangement of B. X. contacts of a sclecting'd'evice according to the invention.

As can be seen best from the Fig. 1, the contact lbank 1 of the selecting device contains vertically disposed contact rows, each having ten sets of contacts. Each contact set consists as usual of three contacts, viz the a, b, and c contacts (Fig. 3). Two switch rods 3 and 4 are movably mounted in the supports 5 and 6 and are located next to each other parallel to the cont-act plane of the bank. The lower end of each rod is provided with teeth; the front rod 3 has teeth 7 and 8 on both sides for the operating pawls 10 and 1l and for the holding pawl 12, while the rod 4 located behind rod 3 has teeth only on the right hand side, for the operating pawl 11 and the holding pawl 12. The rod 4 located in back of the rod 3 carries movable sets of contacts 2. These are out of engagement with the stationary contacts 13 of the bank when -the selecting device is in the normal position of rest. The front rod 3 is provided with projections 14, there being one such projection for each contact arm 2 of the switch. These projections are placed at such a distance from one another that when the rod 3 is moved the distance of one tooth, the lowest projection engages its associated roller 15 of the movable contact 'spring sets carried by the other rod 4; similarly when the rod 3 is moved the distance of two teeth, the second projection from thebottom engages its associated roller 15, thereby pressing the corre- 4 reaches its operative position, inwhich the last projection to -be operative is held in this -position when the 'electromagnet 16 is deenergized.v This magnet -when intermittently energized raises the rod 3 by means of its pawl 10. Next the motor magnet 17 is alternately energized and deenergized,

5 which causes the operating pawl 11 to enter the teeth 8 on both the rods 3 and 4. Thus the magnet 17 raises the rods simultaneously a distance corresponding to the number of current impulses it received. During this lo movement of the rods, the selected set of wipers 2 wipes over the contacts 13 ofthe contact row associated with it and so-sets up a connection with the desi-red line.

The release of the selecting devices can be effected in various ways, forA example like in a switch with vertical and rotary movement by means of rectangular motion as will be described hereafter. In the arrangement shown in Fig. 1, the release would take place 20 when the magnet 18 is energized thereby raising the holding pawl out of the teeth on the rods 3 and 4. so that the two rods are returned to their normal position by their own weight and with the assistance of the spring 19, which was tensionedduring the movement. This construction therefore enables the selecting device to be placed in a horizontal position, in which it would be returned to the normal position merely by the action of the spring. Hence the select-ing device operates exactly according to the* principle of the known Strowger switch with the contact field sub-divided into levels,

except that its contacts are moved in only 5 one direction. It can, therefore, easily be applied to circuits in connection with Strowger switches. l

The Figs. 2 and 3 show on a somewhat larger scale front and side elevations of the upper part of the switch with its contact sets and the bank. The construction of the movable contact sets can be seen better from these figures. Each contract set 2 consists of three 545 punched leaf springs 20a, 206, 20c. which are insulated from one another and are fixed to the plate 21 of a movable lever 22. One end of the lever 22 carries a roller-l5, while its other end is rotatablyfastened to -a projection 23 of the rod 4. On one side of the plate 21 there is provided a leaf spring 24, the free end of which lies against a projection on the supporting piece23 pressing the lever 22 with its rollerl against one of the narrow edges of the rod 3. In this position the contact springs 20 a. b. and c are maintained out of the contact plane of the stationary contacts 13 of the bank 1. By means of slots in the plate 20, each contact is divided into two arms, one of which wipes over the stationary contacts 13 of the bank, while the other is pressed against the rails 25 located between the stationary contacts,

which rails serve to conduct current to the movable contacts in their operative position.

Between the individual tens levels of the bank there is an auxiliary contact 26, which is associated with the 0 arm of the movable contacts. This auxiliary contact 26 is brought into electrical contact with the o arm before it reaches the other cont-acts of the contact bank and is used as a test contact, digit contact or for signalling purposes. But these auxiliary contacts can also be located at the commencement-'or end of the contact bank and can be wiped over by a. separate contact arm during the positioning movement.

In Fig. 3 is shown a form of construction for the-selecting device, in which there is only a single operating magnet instead of two motor magnets and a release-magnet. This single magnet 27 by means of its arma ture 28 controls the operating pawl 29, which is in engagement withthe teeth 8 of the rod 3 and raises the rod 3 step by step when current impulses are delivered to the magnet 27. Now in order to raise both the rods 3 and 4 by means of the same magnet during the succeeding impulse transmission, the switch is provided with a special coupling device, which automatically couples and unA couples the rod 3 with the rod 4 carrying the contact sets 20, a., b, c, after the rod 3 has been positioned. For this purpose teeth 30 are provided above the teeth 8 of the rod 4. which cooperate witha vspring `lever 31 of the rod 3. The lever31 has an inwardly directed extension piece 32, which is located below the teeth 30 of the rod 4 when the switch 'is in its normal position. When the rod 3 is displaced, the teeth 30 of the rod 4 come within rangel of the-extension piece 32 on the lever 31. but, owing to the comparatively fast motion of the rod 3, the lever 31 does not prematurely fall into the gaps between the teeth. Only at the end of the movement can the extension piece 32 of the lever 31 enter a tooth gap, thereby coupling the rods 3 and 4 together. If current impulses are ,again sent to the motor magnet 27 both rods are moved together. The selected wiper set, in a manner already described, is

thereby moved over the stationary contactsy of the contact bank, (not shown), and comes to rest on reaching the wanted contact.

Now in order to release the connection, the displaced parts of the switch have to be returned to their normal position. To effect this, the motor magnet 27 is again alternately energizedI and deenergiz'ed, thereby causing both rods to be further raised step by step. Vhen the rods take their last step the projecting lower end 33 of the rod 4 comes against the holding' pawl 35 and lifts it as welll as the operating pawl 29 out of their Y teeth. They are held in this posit-ion by a lever 34, which is controlled by a. spring and passes behind the projection on the holding pawl 35, thus locking both pawls in their inllo operative position. The rods 3 and 4 can now fall back under the action of their own weight. The uncoupling of the two rods 3- l-out of the teeth and so permits the rod 3 to fall down to its lowest position. An ex-y tension 37 on the rod 3 presses the arresting lever 34 back into its original position when the normal position is reached. Both pawls 29 and 35 are released and again enter the teeth 8.

The example shown in the Fig. 5, which only shows those parts of the switch that are required Jfor umlerstanding the method of working, differs trom the previously described examples only in that the coupling member comprises a pendulum instead ot' a spring lever. The pendulum, is located on rod 4 and its extension piece wipes over the teeth 3l) ot the rod 3 when this rod is moved, thus causing it to oscillate.. Furthermore in place of the fixed stop 36 for uncoupling the lever 31, an arm 38 is provided on the holding pawl 35. In its inoperative state this arm assumes such a position, thatthe pendulum 39 is lifted out of its engaging position (shown dotted) when the rod 3 reaches its normal position. The other operations remain the same. pendulum permits the switch' to operate slower than when a spring lever is used.

Fig. 6 shows another construction of tlnJ coupling member.

rod 3,. however, and in the normal position of the switch as well as duringtthe displace.- ment of the rod 3 the one arm 40 of its lever 31 lies on the fixed sto 41, thus keeping x it out of engagement wit 1 the teeth 3() ot' the 42 is fixed to the rod 3. It has a stop 43,

which is located in front of the teeth 30 of the rod 4. During the upward motion of the rod 3 it carries with it the escapement 42, the stop 43 of which is deviated by the gaps of the teeth 30, thus causing the escapement 42 to oscillate. Only when the positioning of the rod 3 has been completed can the stop 43 enter the gap of the tooth lying in front of it in the rod 3, -thus coupling the two rods together.- They are again uncoupled by the fixed stop 41 likel in the ar- A rangement shown in Fig.v 6; when the nose The use of v"a v It likewise takes the vform ot' a pendulum; here itis fitted to the 40 reaches the stop 41, it lifts the stop 43 out of the tooth, thus releasing the two rods 3 and 4.

In the arrangement shown in Fig. 8 the rods 3 and 4 are coupled mechanically and are uneouplcd oleetro-maguetically hy means ofe the auxiliary magnet 44, which is mounted onthe switch. The coupling niember 31 fitted to the. rod 4 forms the armature of the auxiliary magnet 44 and is controlled by a spring 45. which presses the engaging end 32 of the coupling lever 3l against the teeth 30 on the rod 3 when the auxiliary magnet 44 is deenergized. lVheu the switch is in its normal position, the engaging,r part 32 is located above the teeth 30. 1n order to prevent it entering the teeth during the movement of the rod 3, the auxiliary magnet 44 is energized at the commencement of the positioning movement of the switch rod and remains energized until this movement has ended. vWhen the aux! iliary magnet is deenergized, the part 32 of the coupling member 31 engages the tooth 30 that happens to be in front of it, whereby the two rods 3 and 4 are coupled together and can be moved simultaneously. Upon the release ofthe switch, the auxiliary magnet 44 is again energized in order to move the coupling member 31 out of a gap of the teeth and to hold it in its operative position ,until both rods in falling down have reached their normal position.

Figure 9 shows a modification of the construction shown in Fig. 8. 'In this figure the coupling armature 31 is lifted mechanically out of the teeth of the rod 3; hence it is not necessary to again energize. the auxiliary magnet 44 during the release movement of the switch. At the commencement of the positioning movement of the rod 3, the energizing of the auxiliary magnet 44 brings the coupling armature 31 into an inoperative position with respect to the teeth 30 on the rod 3. With the coupling member 31 in this osition, a hook 56 fixed thereto places itseli) behind the projection 57 on the krod 4 in order to ensure that the latter remains in its normal position during the displacement of the rod 3. This positioning movement of the rod 3 having been completed, the magnet 44 is again dee'nergized, causing the coupling member 31 to drop into one of the teeth 30 that happens to be standing in front of it. Both the rods 3 and 4 can now be moved together in order to set up a connection.

of the rod' 3, and it thus again reaches the lll) llo

After the eonueeof o .tron hasbeen set up, it 1s not necessary to spiral spring 58 is tensioned, which serves to assist the release movement of the rod 3, in order that the selected contact set 2 may reach its initial position outside the bank `the invention, in'which the movable contacts are held over thelr correspondmg levels 1n the bank when the switch position.

With the switch in its normal position, the rod 3 is held by the one extension 46 of the escapement 47 of the motor magnet 48, this extension, piece 46 engaging the teeth ot' the rod 3, and the rod 4 is held by the armature 49 ofzthe magnet 50; in the normal position of the switch, the pawl shaped part 51 of the armature 49 lies under a ro- ]ection 52 on the rod 4 and so holds it. ach time the motor magnet 48 is energized, its armature 53 brings the extension of the escapement 47 out of its engaging position, while the movable pawl v54 on the escapement 47 catches the opposite tooth located on the other side of the rod 3; thus each time the armature 53 is attracted, the rod drops approximately the distance of one tooth. When the magnet 48 is deenergized, the armature 53 moves back to its normal position and allows the rod 3 to drop the remainder of one tooth,` thereby causing the displaced contact point to be again moved in order to ensure that contact is established is in its normal in a reliable manner.

After the selected contact set has been brought into its operative position, the magnet is energized and its armature 49 with its pawl shaped part 51 ismoved away from the projection 52 on the rod 4. Hence when the motor magnet 48 is operated, the two rods .Which when operated causes its pawl 56 to engage the teeth of the rods 3 and 4, thus raising both rods step by step. The return motion of the rod 4 is ended 'when its projection 52 comes in front of the pawl 51 of the armature 49 and so enables it to drop in. During the further actuation of the pawl 56 the rod 3 is raised until the extension piece 46 of the escapement 47 passes under the last tooth of the rod 3. The electromagnet is now deenergized and the selecting device is again ready to setup another" connection.

It is obvious thatthe coupling of the rod 4 to the rod 3 can be effected in a different manner to that described, for example by means of mechanical coupling members of the kind explained already with reference to Figs. 549. Furthermore a motor drive can be used in place of the special magnet for returning the rods from their operated to their normal position, the motor drive thusI performing the functions of the magnet.

For the purpose of effecting in a simple manner the necessary switching over of the auxiliary contacts during the positioning and arresting of the switch, a contact spring set 57 is provided at one side of the rods. This spring set is under the control of a switch lever v58, the .lower end of which is loosely mounted on a stationary part of the selecting device. TheA lever carries a roller 59, which engages depressions 60 in the switch rods 3 and 4 when the selecting device is in its normal position. In this position an insulated extension piece touches a pin 61 of the middle contact spring of the spring set 57 and keeps one contact closed. On moving` the rod 3 out of its normal position the depression 60 is removed from the roller 59, thusrpressing the lever 58 against t-he pin 61 of the contact spring and effecting a circuit change. The lever 58 is held in this position until both rods 3 and 4 have again assumed their normal position, in which both depressions assume such a position that they permit the roller 59 of the lever to drop in.

In the above described arrangement, the contactspring set 57 is under the control of both rods 3 and 4 in order to designate the normal condition of the switch. It is obvious that the arrangement could be such 'that the auxiliary contacts are controlled by either of the switch rods, in order to effect circuit changes in the levels or groups.

The displacement of the switch rods 3 and 4 with respect to each other also permits of a very simple construction of contacts provided for multipleand other purposes, as shown by way of example in the Figs. 11 and 12.

For this purpose a set of contact teeth 62 are fixed to the rod 3 by means of insulating pieces, as shown in the arrangement of the Figs. 11, and a connecting member having two wiping springs 63 and 64 is fixed to the rod 4.' The upper spring-'63 cooperates with the contact teeth 62 on the rod 3 and the other spring 64 of the connecting memloof llt)

ber 65 cooperates with the Contact teeth 66 iixcd to the switch hy means of insulation. In the present example it has been 'assumed that multiple contacts are provided in the 3rd, 4th and 5th level. Hence during the 62. During the succeeding simultaneous.

movement of both rodsl 3 and v4, the lower wiper spring 64 of the connecting member 65 will hunt over the contact teeth 66 fixed to the switch until an idle line is reached.

Fig. 12 shows a modified construction of the above described arrangement. Several connecting members 67 to 70, which are insulated from one another, are provided for setting up the multiple line connections.

It can be seen that by means of each of these contact devices l67---70 multiple line connections (P. B. X. lines) can be set up irrespective of the level in which they are located. The connecting member 67, for example, wipes over the multiple contacts 66 of three subscribers, viz two contacts for one subscriber and three contacts for each of the other two subscribers.- As the same distribution is provided in the level O, the connecting member 67 is also brought into touch with the contact 0 of the teeth 62. In the second level there is a subdivision of 4 and 5 contacts. Hence the level contact 62 is brought into touch with the connecting member 68. In the same manner connection is set up 'by means of the contact member 69 in the levels 3 8, in which multiple line subscribers are provided for, namely two with 2 lines and one with 4 lines. The 9th level is provided with ten subscribers multiple line terminals 66, which are wiped over by the connecting member 70. Hence in the example shown, only 4 connecting members 674-70 are required for all the line terminals. It is obvious that other combinations are possible by adding further Amultiple contacts 66. However, in actual practice the subscribers are usually provided with a similar number of multiple lines, and a small number of connecting members will therefore suiice. A decrease in the number of these connecting members as well as of the weight to be moved will be achieved in this manner.

In order to simplify the construction,Vv the teeth 62 and 66 are formed as shown in Fig. 13 by means of stamped and bent tongues on a metal plate 71, as there is no need to insulate these contacts from each other.

The Fig. 14 shows another construction for forming multiple line connections in a switch of the type described. There are shown a plurality of contact banks 1- corresponding to the Fig. 3, but these are provided with an additional row of d-contacts besides the rows of a, b, and c contacts.

' These d contacts are formed by conductors 13 passing through all the contact banks in common. -Accoidin as they are or are not connected to groun they form a multiple line connection. The contact arm 20d wipes over thesecontacts while the movable contacts`20 are dis laced, and they serve then for selecting an ildle line in the contact groups.`

What is claimed is: 1. An automatic switching mechanism having a plurality of groups of stationaryl contacts arranged in vertical rows one above the other, a member movable parallel to said contacts and provided with movable sets of wipers in number corresponding to the nu`m` ber of Contact groups, a second member movable parallel to said contacts and provided with projections in number corresponding to the number of wiper sets on said first member, means for moving said second member to operatel a desired` wiper set into -engage-l ment with the group of contacts corresponding thereto, and means for moving both said members simultaneously to position said vselected set of wipers upon a desired set of contacts in said corresponding group.

2. An automatic switching mechanism having a plurality of groups of stationary terminals arranged in vertical rows one above the other, a member movable parallel to said terminal groups and provided with movable sets of wipers in number correspondino to the number of terminal groups, a second member movable parallel to said first member and provided with a plurality of projections one for each set of wipers, means formoving said secondmember to operate a desired wiper set into engagement with the group of terminals corresponding thereto, means for locking both members to each other,- and means for then movin bothmembers simultaneously to operate sai positioned set of wipers into engagement with a desired set of terminals within said corresponding group.

3. An automatic switching mechanism having a plurality of groups of stationary .terminals arranged in sets in vertical .rows

one above the other, each group containing a plurality of sets ,of terminals, a switching member movable parallel to said terminal groups and provided with movable sets of wipers, one set for each group of terminals, said wiper sets being located upon said member opposite their corresponding groups but out of engagement therewith, a second switching member movable parallel to said first member and provided with a plurality of rojections, one for each set of wipers, Sai projections bein'g vertically displaced on said second member relative to said sets,

of wipers to permit engagement with the corresponding wiper sets in succession when said second member is moved with relation to said first member, means for moving said second member to select a desired set of wipers and to move said set into operative relation with the group of terminals correspending Sucreto, means for coupling both members to each other, and means for then moving both members simultaneously to move said selected set of wipers into engagement with a desired set of terminals within -said corresponding group.

.ber opposite their corresponding groups but out of engagement therewith, a second switching member movable parallel to said first member and provided with a plurality of projections, one for each set of wipers, said projections being vertically displaced on said second memberrelative to said setsof lwipers to permit engagement with the corresponding wiper. sets in succession when said second member is moved with relation to said lirst member, means for moving said ysecond member to select a desired set .of

wipers and `to move said set into operativel relation with the group of terminals correspondin thereto, mechanical means for automatically coupling both said members to each other, and means for then moving both members simultaneously to movev said selected set of wipers into engagementy with a desired set of terminals within said corresponding group.

5. An. automatic switching mechanism havingl a plurality of groups of stationary terminals arranged in sets in vertical rows one above the other, each group containing a plurality of sets of terminals, a switching member movable parallel to said terminal groups and provided with movable sets of wipers, one set for each group of. terminals,

vsaid wiper sets being located upon said meml ber opposite their corresponding groups but out of engagement therewith, a ysecond switching member movable parallel to said first member and provided with a plurality of projections, one'for each -set of wipers, said projections being vertically displaced on said second member relative to said sets of wipers to permit engagement with the 6. An automatic switching mechanism having a pluralityv4 of groups ot stationary terminals arranged in sets in vertical rows one above the other, each group containing a plurality of sets of terminals, a switching member movable parallel to said terminal groups and provided with movable sets of wipers, one set for each group of terminals, said wiper sets being located upon said member opposite their corresponding groups but out of engagement therewith, a second switching member movable parallel to said iirst member and provided with a plurality of projections, one for each set of wipers, said projections being vertically displaced on said second member relative to said sets of wipers to permit engagement with the corresponding wiper sets in succession when said second member is moved with relation to said first member, and a single electromagnetic means for first moving said second member to select a desired sct ot' wipers to move said wipers into operative relation with the group of terminals corresponding thereto, and for then moving both switching members simultaneously to move said selected set ot wipers into engagement with a desired set of terminals within said corresponding group.

7. An automatic selecting device having groups of stationary terminals, a irst shaft being vertically movable and provided with means for selecting a group, a second movable shaft disposed parallel to said first shaft and' provided with means for selecting terminals, and single electromagnetic means operable for {irst'moving said firstl shaft to select a desired group and then operable ,for

moving .said second shaft to select desired terminals within said selectedgrovup.

8. An automatic selecting device having groups of stationary terminals, a first shaft being vertically movable and provided with means for selecting a group, a second movable shaft disposed parallel to said first shaft and-provided with means for selecting terninals, and electromagnetic means operable for moving said first shaft independent of said second shaft to select a desired group, and then operable for moving both shafts simultaneously to select desired terminals within said selected group.`

9. An automatic selecting device having groups of stationary terminals, a first shaft being vertically movable and provided with means for selecting a group, a second inovable shaft disposed parallel to said .first shaft. and provided with means for selecting terminals, means for moving said first shaft independent of said second shaft to select a desired group, means for locking said first l shaft to said second shaft, and means for then moving both shafts simultaneously to llf) select desired terminals .within said selected group.

of stationary terminals disposed in a single plane, a plurality of independently movable shafts disposed parallelto said plane and provided with means for selecting desired terminals in said groups, and single electromagnetic means for imparting straight line successive movements to said shafts to first select a group and then desired terminals within said group.

11. An automatic switch having groups of stationary terminals disposed in a single plane, two independently movable shafts provided with group selecting means and with terminal selecting means, and single electromagnetic means for first moving one shaft to select a group and for then moving both shafts simultaneously to select desired terminals within said selected group.

12. An automatic switch having groups of stationary terminals disposed in a single plane, two independently movable shafts provided with group selecting means andv with terminal selecting means, and means for first moving one shaft to select a groupv andl for then moving both shafts simultaneously to select desired terminals within said selected group, said shaft movements being executed in succession and said terminal plane. 4 13. An automatic switch having groups of stationary terminals disposed in a single plane, two independently movable shafts provided with group selecting means and with terminal selecting means, means for irst moving one shaft' to select a group, means for automatically locking both shafts together upon the termination of said rst movement, and means for then moving both shafts simultaneously to select desired terminals within said selected group.

14.' An automatic switch having groups of stationary terminals disposed Vin a single plane, two independently movable shafts provided with group selecting means and with terminal selecting means, means for first moving one shaft to select a group, means for automatically locking both shafts together'upon the termination of said first movement, and -means for then moving both shafts simultaneously to select desired terminals within said selectedA group, said shaft movementsbeing executed in succession and in a. direction parallel to said terminal plane. A. v

15. An automatic switch having groups of stationary terminals, movable wipers, provisions to position said wipers upon desired terminals within said groups, and single electromagnetic means for executing the selection of a group and of terminals within a parallel to group by two successive straight line 4movements of `said provisions.

16. An automatic switch having groups of stationary terminals, movable wipers,` provi/sions to position said wipers upon deslred terminals within said groups, and single electromagnetic means for executing the selection of a group and of terminals within a group by two successive Straight line movements of said provisions, the direction and plane of both movements being the same.

17. An automatic switch having groups of stationary terminals arranged in a single plane, movable wipers, movable means to position said wipers upon desired terminals, an electromagnet, and means for executing the selection of a group and of terminals within a group by a succession of straight line movements imparted to said positioning means by said electromagnet.

18. An automatic switch having groups of stationary terminals arranged in a single plane, movable wipers, means zcomprising two independently movable shafts to position said wipers upon desired terminals, an electromagnet, and means for executing the selection of a group and of terminals within a group by a succession of straight line movements imparted to said shafts by said electromagnet, the direction and plane of said movements being the same and parallel to the terminal plane.

19. An automatic switch `having groups of stationary terminals arranged in a single plane, movable wipers, a plurality of independently movable shafts to position said wipers upon desired terminals, an electromagnet, and means for executing the selection of a group and of terminals within said group by a succession of straight line movements imparted to said shafts by said electroma net.

20. n automatic switch having groups of stationary terminals arranged in a single plane, movable wipers, a plurality of independently vmovable means to position said wipers upon desired terminals, an electromagnet, and means for executing the selection of a group Vand of terminals within said group by first imparting movement by means of said electromagnet to anly one of said positioning means and thento all of said positioning means simultaneously.

21. An automatic switch having groups of stationary terminals arranged in a single plane, movable wipers, a plurality of independently movable means to position said wipers upon desired terminals, an electromagnet, and means for executing the selection of a group and of terminals within said group by first imparting movement by means of said electromagnet to only Aone. of said positioning means and then to all of said positioning means simultaneously, the direction and plane of said movements being the same and parallel to said terminal plane.

In witness whereof, I hereunto subscribe my name this 10th day of February, A. D. 1927.

' -ALEXANDER BRUNO PREUSS. 

